JP2000079462A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a brazing property and brazing strength of a heat transfer fin by winding a corrugated plate in the direction of a corrugation to form an annular heat transfer fin, bringing the heat transfer fin into contact with a tube wall of a heat exchanger and arranging it and forming a groove which holds a brazing filler metal in the outside of the apex of the corrugation of the heat transfer fin which comes into contact with the tube wall. SOLUTION: A steel strip is formed into a corrugated plate having a prescribed pitch with a press, and a brazing filler metal holding groove 29 is simultaneously formed in the apex 27 of a corrugation which is formed in a flat plate part capable of coming into surface contact with a tube wall. The corrugated plate is bent into an annular shape to form a heat transfer fin 30. The depth of the brazing filler metal holding groove 29 is specified to 0.2-0.8 mm, preferably 0.3-0.5 mm. A paste-like brazing filler metal is filled in the brazing filler metal holding groove 29 or a bar-like brazing filler metal is fit into the groove, the heat transfer fin 30 is inserted into a heat exchanger tube body 28, brazing is executed by being passed through a heating furnace for brazing, and a heat exchanger is formed. The thickness of the corrugated plate is specified to 0.01-0.8 mm, preferably 0.05-0.5 mm. The pitch of the corrugation is preferably specified to 2-6 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat exchanger and a method for manufacturing the same. In particular, a heat exchanger that exchanges heat by passing high-speed high-temperature gas (gas) through the inner pipe and cooling water (liquid) through the outer pipe, for example, an exhaust cooler that cools exhaust gas of an internal combustion engine with cooling water (High heat exchange capacity is required)
This is a preferred invention.

Here, a double-pipe heat exchanger will be described as an example, but the present invention is not limited to this.

[0003]

2. Description of the Related Art As shown in FIGS. 1 and 2, a double-pipe heat exchanger is one in which an inner pipe 12 is inserted into an outer pipe 14 and both ends of the outer pipe 14 are welded to the outer wall of the inner pipe 12. is there. Outer tube 14
The cooling water inlet nozzle 16 and outlet nozzle 18 are formed at both ends so that they can be used in countercurrent / cocurrent (countercurrent in the example in the figure). In addition, 20 is a pipe flange.

In the configuration shown in FIGS. 1 and 2, heat exchange is performed only on the wall surface of the inner tube 12, the heat transfer area is small, and
Heat exchange of the fluid flowing through the center of the inner tube 12 is difficult, and the heat exchange efficiency is low. That is, it was difficult to obtain a large heat exchange capacity as a whole.

For this reason, as shown in FIGS. 3 and 4, a multi-tube type in which a plurality (four in the illustrated example) of small-diameter inner tubes 12A are inserted into the outer tube 14 is usually used. Have been.
With this configuration, the heat transfer area is increased, and heat exchange can be performed with respect to the fluid flowing on the central portion side, so that a large heat exchange capability is easily obtained.

However, the multi-tube type shown in FIGS. 3 and 4 tends to increase the number of manufacturing steps and increase the weight.

[0007] For this reason, the inventors of the present invention have previously described FIG.
In the double-pipe heat exchanger having the configuration shown in FIG. 2, a heat transfer fin 22 formed of a corrugated tube having a radial cross section is brought into contact with the inner pipe 12 as shown in FIG. (Japanese Patent Application No. Hei 9-182571 (filed on Jul. 8, 1997): see Japanese Patent Application Laid-Open No. Hei 9 (1998), not disclosed at the time of filing). The heat transfer area can be increased and the fluid flowing through the center of the inner tube 12 can be exchanged with heat, thereby increasing the heat exchange capacity.

In the heat exchanger having the structure shown in FIG. 5, the heat transfer fins 22 are formed by winding a corrugated sheet 24 cut into a predetermined length at a predetermined pitch P and a predetermined height H as shown in FIG. The crest 2 is placed on the wall of the inner tube (heat exchange tube) 12.
The outer side of the crest was fixed by brazing.

[0009]

The brazing is performed by applying a brazing material (paste) to the outside of the crest 25 and inserting the heat transfer fins 22 into the heat exchange tube 12. The semi-finished exchanger was put into a brazing heating furnace, and was taken out after a lapse of a predetermined time.

However, in the case of this brazing method, it is found that stable brazing properties and brazing strength cannot be obtained between the crests 25 of the heat transfer fins 22 and the tube wall of the heat exchange tube 12. Was.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a heat exchanger in which the brazing property and brazing strength of a heat transfer fin can be stably obtained, and a method of manufacturing the same.

[0012]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive efforts for development, and in the above-mentioned manufacturing method, the brazing material applied to the outside of the crest 25 is
At the time of insertion into the inner tube 12, it partially interferes with the inner wall surface of the inner tube 12, or is moved or dropped, and at the same time, the crests 25 of the heat transfer fins 22 contact with the heat exchange tube 12 tube wall. It was found that the heat exchanger did not flow into the gap, but rather flowed down to the other part. Thus, a heat exchanger having the following structure and a method for manufacturing the same were conceived.

In the heat exchanger according to the present invention, the heat transfer fins formed by winding a corrugated sheet of a predetermined length at a predetermined height and a predetermined pitch in a wave direction are formed inside or outside the tube wall of the heat exchange tube or In a heat exchanger in which the outer side of the crest is placed in contact with the opposite tube wall of the annular space formed by the double tube and the outer side of the crest is brazed, the crest that contacts the tube wall of the heat transfer fin A brazing material holding groove is formed on the outside.

In the above heat exchanger, it is desirable that the wave crest portion on which the brazing material holding groove is formed is formed in a flat plate shape capable of making surface contact with the tube wall to be contacted.

According to the method of manufacturing a heat exchanger of the present invention, a heat transfer fin formed by winding a corrugated sheet of a predetermined length and a predetermined pitch in a wave direction at a predetermined height and a predetermined pitch is formed inside the pipe wall of the heat exchange pipe. Alternatively, in a method for manufacturing a heat exchanger, the method includes a step of arranging an outer side of a crest in contact with an outer tube wall of an annular space formed by an outer or double pipe and brazing the outer side of the crest. A brazing material holding groove is formed outside the wave crest in contact with the tube wall of the heat fin, and the brazing material is held in the brazing material holding groove in a process prior to disposing the heat transfer fin in contact with the heat exchange tube. It is characterized by.

In the method for manufacturing a heat exchanger, the brazing material holding groove is desirably formed at the same time that the crest is press-formed into a flat plate shape so that the crest can come into surface contact with the tube wall.

[0017]

The heat exchanger and the method of manufacturing the same according to the present invention are characterized in that the brazing material holding groove is formed outside the wave crest of the heat transfer fin to be brazed to the heat exchange tube. The heat transfer fins can be set on the heat exchange tube in a state where the brazing material is applied to the grooves or the bar-shaped brazing material is set.

For this reason, in the brazing and heating step, the brazing material flows into the contact gap between the crests formed on both sides of the brazing material holding groove and the tube wall. Therefore, stable brazing properties can be ensured.

In particular, by forming the crest where the brazing material holding groove is formed into a flat plate shape so that the surface of the contacting tube wall can be brought into contact, the brazing area can be easily secured, and more stable brazing property and Easy to secure brazing strength.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(1) A case where a corrugated plate 26 as shown in FIG. 7 is brazed and fixed to a heat exchange tube (inner tube) 28 as shown in FIG. I do. In the sectional view of FIG. 8, the outer tube is omitted.

The corrugated plate 26 is formed as a U-shaped bent portion (first bent shape) U having bent portions on both sides of a crest portion 27 on the brazing surface side (the outer circumferential surface side), and the inner circumferential surface side. V side
A bent portion (second bent shape) V is formed.

The method of preparing the corrugated plate 26 is not particularly limited, and can be prepared by a conventional method. Rolling a gear-shaped punch on a corrugated die, such as drawing, may be performed, but usually,
As shown in FIG. 9, the upper die (push die) 32 and the lower die (receiving die)
34 is set on a press machine, and a metal strip (material) 3
It is desirable to form 6 by sequentially feeding (lifting up by one step by a cylinder or the like and feeding by a fixed length) so that a corrugated sheet of a predetermined pitch can be accurately formed.

At this time, in the present embodiment, the convex ridge 32a and the concave ridge 34a for forming the brazing material holding groove are formed between the upper die 32 and the lower die 34. The brazing material holding groove 29 can be formed.

The cross-sectional shape of the brazing material holding groove 29 at this time is not limited to a rectangle, a trapezoid, a triangle, or the like, but it is preferable to use a semi-circular shape from the viewpoint of preventing material cut. The magnitude of R at this time, that is, the R (depth) of the brazing material holding groove 29 varies depending on the size of the corrugated top 27 and the like, but is 0.2 to 0.8 mm, preferably 0.3 to 0.8 mm.
0.5 mm.

Here, the U-shaped bent portion is used on the brazing surface side. However, the same applies to a normal corrugated plate having only a V-shaped bent portion or a corrugated plate having only a U-shaped bent portion as shown in FIG.

The corrugated sheet 26 press-formed as described above
As shown in FIG. 10, the winding forming of the heat exchange tube body 28, for example, a V-shaped bent portion on the side opposite to the brazing side is performed step by step.
It is desirable to perform the expansion by projecting and bending.

This bend forming is performed by, for example, an upper die (punch) 52 and a lower die (die) 54 as shown in FIG. That is, the upper mold 52 includes a punch block 52a and a punch portion 52b, and the lower mold 54 includes a die block 54.
a and a bifurcated die 54b via a neck 54c.

Next, the brazing material 36, 3 is attached to the crest (outer side surface of the U-shaped bent portion U) 27 of the wound heat transfer fin 30.
6A is applied or set. That is, the brazing material holding groove 2
9 is filled with a paste brazing material 36 as shown in FIG. 12, or a bar brazing material (for example, copper wire) is fitted as shown in FIG. In the case of the bar-shaped brazing material 36A, it is desirable to use a bar material having a diameter (for example, 2R + 0.1 mm) larger than R of the holding groove so as to be fitted into the brazing material holding groove 29 in a tight fit. This is because the rod-shaped brazing material 36A becomes difficult to fall off.

The heat transfer fins 30 on which the brazing materials 36 and 36A are set are inserted into the heat exchange tube 28 as in the conventional case. At this time, since the brazing material is held in the holding groove,
Even if it comes into contact with the tube wall of the heat exchange tube 28, there is no possibility that the brazing material will move or fall off.

Then, the heat transfer fins 30 are brought into close contact with the inside of the heat exchange tube 28 by springback. In this state, the brazing of the heat exchanger is completed by passing through a brazing heating furnace.

At this time, at the time of brazing and heating, the molten brazing material flows into the gap between the holding groove and the tube wall contact portions. Therefore, stable brazing strength can be secured.

The thickness of the corrugated sheet 26 varies depending on the material, but when it is made of steel, it is usually 0.01 to 0.8 mm, preferably 0.05 to 0.5 mm. If the thickness is too small, the heat transfer resistance is increased together with the shape retention, and if the thickness is too large, the weight increases, which is not desirable.

The relationship between the inner radius r of the inner tube 12 and the height H of the corrugated plate 24 depends on the inner diameter of the inner tube 12.
H / r = 0.1 to 0.1 to 50 mm
0.8, desirably, H / r = 0.2 to 0.7.
And according to the range of the inner diameter, the height of the wave peak is H = 4 ~
20 mm.

The wave pitch of the corrugated plate 26 is set to 2 to 6 mm corresponding to the required heat transfer area.

The heat exchange tubes (inner tubes) 12, 14, 2
8 is desirably as thin as possible from the viewpoint of heat transfer, but since rigidity is required as compared with the heat transfer fins 30,
Be thicker than the heat transfer fins. For example, when the inner diameter of the inner tube 12 is in the above range, it is usually 0.1 to 1.0 mm, preferably 0.3 to 0.8 mm.

The location of the heat transfer fins 30 is not limited to the inside of the heat exchange tube (inner tube) 28, but may be an outer peripheral surface as shown in FIG. 14, and further, as shown in FIG. It may be set in the annular portion of the double pipes 12, 14.

[Brief description of the drawings]

FIG. 1 is a front view showing a conventional double tube heat exchanger.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a front view showing an example of a conventional multi-tube heat exchanger.

FIG. 4 is a sectional view taken along line 4-4 in FIG. 3;

FIG. 5 is an enlarged end view corresponding to FIG. 2 in which a heat transfer fin of a corrugated tube is provided on the inner tube in FIG. 1;

FIG. 6 is a perspective view showing an example of a corrugated sheet.

FIG. 7 is an end view showing an example of a corrugated sheet suitable for applying the present invention.

FIG. 8 is an end view showing a state in which the corrugated sheet of FIG. 7 is mounted on a heat exchange tube.

9 is a cross-sectional view showing a forming die when the corrugated sheet of FIG. 7 is press-formed.

FIG. 10 is an explanatory view showing one embodiment of winding and forming the heat transfer fin of the present invention.

FIG. 11 is a cross-sectional perspective view of a punching die used for winding and forming a corrugated sheet.

FIG. 12 is a perspective view showing one embodiment of a brazing material set on a crest in the heat transfer fin of the present invention.

FIG. 13 is a perspective view showing another brazing material setting mode.

FIG. 14 is a schematic end view showing another assembling mode of the heat transfer fin.

FIG. 15 is a schematic end view showing still another assembling mode.

[Explanation of symbols]

 12 inner tube 14 outer tube 22 heat transfer fin 24 corrugated plate 25 crest 26 corrugated plate 27 crest 28 heat exchange tube 29 brazing material holding groove 30 heat transferring fin 36, 36A brazing material V V-shaped bending portion U U-shaped bending Department

Continuation of the front page (72) Inventor Tadao Kitahara 7-11 Shirokane, Showa-ku, Nagoya-shi, Aichi F-term in Maruyasu Kogyo Co., Ltd. 3L103 AA01 AA11 BB17 CC02 CC27 DD08 DD34 DD38

Claims (4)

[Claims] 1. A heat transfer fin formed by winding a corrugated sheet of a predetermined length and a predetermined length in a wave direction at a predetermined height and a predetermined pitch into an annular shape inside or outside the heat exchange pipe wall or a double pipe. A heat exchanger in which the outer side of the crest is disposed in contact with the opposite tube wall of the annular space, and the outer side of the crest is brazed. A heat exchanger, wherein a holding groove is formed. 2. The heat exchanger according to claim 1, wherein the wave crest on which the brazing material holding groove is formed is formed in a flat plate shape capable of making surface contact with a tube wall to be contacted. 3. A heat transfer fin formed by winding a corrugated sheet of a predetermined length and a predetermined length in a wave direction at a predetermined height and a predetermined pitch into an annular shape inside or outside the heat exchange pipe wall or a double pipe. A method for manufacturing a heat exchanger, comprising the steps of: placing a crest outside on a facing tube wall of an annular space in contact with an annular space; and brazing the outside of the crest to manufacture the heat transfer fin. Forming a brazing material holding groove on the outer side of the wave crest, and holding the brazing material in the brazing material holding groove before disposing the heat transfer fins in contact with the heat exchange tube. Exchanger manufacturing method. 4. The heat exchanger according to claim 3, wherein the brazing material holding groove is formed at the same time that the crest is press-formed into a flat plate shape so that the crest can come into surface contact with the tube wall.